Cablecom Modem and IP Subnetting?

I just switched from Swisscom->Cablecom and am having trouble understanding how IPaddressing works with cable-modems With DSL, it was very simple: my modem had an internal address 192.168.1.1 and I could statically assign IP addresses in my home network within that subnet (192.168.1.x), no problem.

I received yesterday from Cablecom a Scientific Atlanta modem EPC2203, and had some trouble getting and IP address assigned to it, after several re-starts, I finally got something, but very weird. First of all, to log in the modem, the IP address is 192.168.100.1 (had to google that), and there's no settings there to change, just one info screen

Then, the IP address of my Win XP laptop is 80.219.30.231 (255.255.240.2) and the default gateway is on a different subnet at 80.219.16.1 (!!). Then I noticed another device on my home network was assigned the IP 80.219.28.x (!!). my Windows 7 PC is not getting assigned any IP address at all.

How is it possible that I am getting assined multiple, non-private IP addresses on different subnets?? And on some devices I'm not getting assigned any IP address at all. When I try to assign static IP addresses, they don't seem to work either, and actually considering the different subnets, I'm not even sure what subnet I should assign a static IP on

When I connect Wireshark I'm seeing even more crazy IP addresses, I guess neighbours stuff since cable networks broadcast to several modems and yours just filters out packets for yours (right?)

I have ordered the new Thomson wifi modem from Cablecom, so I'm hoping that will give more options for homenetworking. But at the moment, I'm really confused

It sounds like you are not using a router with the modem. Typically you would connect a wireless router to the modem by ethernet.

No, I just have a switch connected, not a router. You could be right, this could be a problem, all the other modems I had before had routers built in them. But still, doesn't this "basic" modem have a DHCP server in it? And shouldn't it be able to assign IP addresses to several devices? Or it can only connect to one PC and that's it?

It's just a plain old modem...wait for the Thomson.

http://www.cisco.com/web/consumer/su...s2/4012160.pdf

Nope - it just passes the address given to it by your ISP to your computer

Again no, as it doesn't function as a DHCP server

Correct. To be able to connect several computers to it it will need a standard router (one with an ethernet WAN port, not a DSL WAN port) in between the modem and the switch.

Ok, things are a little clearer now. Thanks I gotta get that Thomson modem/router and then I'll be good to go. I looked in my basement, but could only find ethernet switches, not any routers. Well, I have my Swisscom modem/router still, but not sure if/how to reconfigure that to distribute the Cablecom signal, I think it's just for ADSL Anyway, won't waste time screwing with that, I'll just go swap this for the Thmoson tomorrow at the Cablecom service point in Bern.

I asked specifically for the Thomson when I ordered my internet connection, and was told 3 times by 3 different Cablecom people that I would get it, but when I opened the box yesterday it was this 10 year old crap modem inthe box Guess I have to get used to not having the stellar Swisscom customer service anymore Oh well, Cablecom is cheaper and faster, so there is/will be a bright side...eventually, hopefully

PS- If this modem can only connect one device, how do I have 2 devices connected to the internet right now??

Plug the router into the Modem, and your clients into the router...

you're on the 25Mbps package with two public IPs. Plug a router in (WAN port) and have dhcp deal up your NATted devices.

what's interesting for me is you ask this question but have Wireshark..........!!

Yea, I was assuming the modem had routing and DHCP abilities, but now I see it doesn't. This modem model is almost 10 years old, I can't believe they sent me this ancient crap in this day and age. I'm going to exchange it for the Thomson modem/router today so I can have something more "modern" and bring my home network back up on-line.

...but still something is strange, because yesterday, once the modem finally got itsself up and on-line (took maybe 1-2 hours, guess it had to do some ranging or whatever, for a first-time installation), but then I was only able to get my Win XP netbook to be assigned an IP address. If I connected my Win 7 laptop, it would not connect, ever, either DHCP or static IP. Then today, I restart the modem, and after 1-2 hours of waiting for a stable internet connection, my Win 7 laptop was finally assigned an IP address. Everything else being exactly the same (Of course I'm only connecting 1 device at a time to the ethernet port of the modem).

Anyway, like I said, modems going back... and I'm glad I have a 3G data modem to keep me on-line for times like these

that's nekkid Internet you're connecting to, too, you know

In the end, I'd recommend a router on your side as you never know who's interested in your private network ......

Call me superstitious but I doubled-NATted my VDSL connection from Swisscom when I had it.....

This earlier post explains how to log on to the Scientific Atlanta EPC2203 modem. The password cannot be copied, and has to be typed manually, and select Level 2 access.

Username: admin

Pwd: W2402

You can see all the stuff about signal strength etc.

Went to the Cablecom "service point" in Bern today at run-down Belpstrasse 36: one Cablecom employee, 4 chairs, 7 people waiting.... 40min later I got the Thomson modem and got into the 2000's (the Scientific Atlanta modem had installation instructions for Windows 95 ). I plugged it in at home and everything is back to normal now.

Actually, last night, the Scientific Atlanta modem kept loosing the internet connection, like every 30 min the DS/US lights would start flashing, 10min later the internet connection would come back, stay for about 10min, then it would start all over again. Maybe the network was still "ranging" my modem or something, but the Thomson has been working all day no problems, and the Cablecom installation manuals only said after 30min all modems should be working normally. So I don't know about that Scientific Atlanta modem, but I'm happy to have the Thomson, and I'm not looking back